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Diarrheal diseases are a major cause of morbidity and mortality in infants and young children, particularly in sub-Saharan countries. In Gabon, there are few data on the prevalence of diarrheal pathogens in children. The aim of this study was to assess the prevalence of diarrheal pathogens in children with diarrhea in southeastern Gabon. Stool samples (n = 284) from Gabonese children 0 to 15 years of age with acute diarrhea were analyzed using polymerase chain reaction targeting 17 diarrheal pathogens. At least one pathogen was detected in 75.7% of samples (n = 215). Coinfection with multiple pathogens was observed in 44.7% of patients (n = 127). Diarrheagenic Escherichia coli was the most commonly detected pathogen (30.6%, n = 87), followed by adenovirus (26.4%, n = 75), rotavirus (16.9%, n = 48), Shigella sp. (16.5%, n = 47), Giardia duodenalis (14.4%, n = 41), norovirus GII (7.0%, n = 20), sapovirus (5.6%, n = 16), Salmonella enterica (4.9%, n = 14), astrovirus (4.6%, n = 13), Campylobacter jejuni/coli (4.6%, n = 13), bocavirus (2.8%, n = 8), and norovirus GI (2.8%, n = 8). Our study provides useful information on the possible causes of diarrheal diseases affecting children in southeastern Gabon. A similar study with a control group of healthy children is needed to assess the burden of the disease attributed to each pathogen.

IntroductionDespite all the efforts made to control or even eliminate malaria, the disease continues to claim the highest number of victims of vector-borne pathogens in the world and Sub-Saharan countries bear the heaviest burden. The lack of knowledge of the role of various protagonists involved in the transmission of this parasitic disease, such as mosquito vectors and the plasmodial species they transmit as well as the host species they infect in a locality, constitutes one of the main causes of the persistence of malaria. In Gabon, in several areas, entomological data on malaria transmission remain poorly known. Thus, this study aimed to determine the diversity of Anopheles involved in malaria transmission in different environments of the province of Nyanga in southwest Gabon.MethodsFor this, an entomological study was carried out in the four main localities of the province of Nyanga to provide answers to these shortcomings. Mosquitoes were collected over several nights using the human landing catch method. The identification of Anopheles and malaria parasites circulating in the different sites was achieved by combining morphological and molecular analysis tools.ResultsA total of five hundred and ninety-one (591) mosquitoes belonging to the Culicidae family were collected. From this collection of adult mosquitoes, nine species of Anopheles mosquitoes notably species of the Anopheles nili complex (53.46%) followed by those of Anopheles gambiae complex (22.01%), Anopheles funestus group (18.24%), Anopheles moucheti complex (5.66%) and Anopheles hancocki (0.63%). Approximately 18 percent of these Anopheles species were infected with Plasmodium spp. Anopheles funestus, known to be involved in malaria transmission to humans, and An. moucheti-like, recently discovered in Gabon, and whose status in Plasmodium transmission is not yet elucidated, were found to be infected with great ape Plasmodium.DiscussionOur results raise the question of the potential switch of simian malaria parasites to humans. If these observations are confirmed in the future, and the infective capacity of the bridge vectors is demonstrated, this new situation could ultimately constitute an obstacle to progress in the fight against malaria.

Objective Variants of concern (VOCs) associated with relatively high transmissibility appear to be spreading rapidly in Gabon. Therefore, it is imperative to understand the distribution of several variants of concern in the population, which could have implications for transmissibility and vaccine efficacy. Methods Between February and May 2021, SARS-CoV-2 genomes were sequenced using the Oxford nanopore MinION method and the respective genome diversity was elucidated. Phylogenetic analysis was performed and genomes were classified using pangolin lineages. Results The results highlight the increase (46%) of the alpha variant of concern (B.1.1.7) in the Gabonese population over the study period. In addition, an increase (31%) in the B.1.1.318 lineage, which is associated with high transmission and impaired vaccine efficacy (D614G+E484K+Y144del), was detected. Conclusion With the second wave ongoing, our findings highlight the need for surveillance of the SARS-CoV-2 genome in the Republic of Gabon and should provide useful guidance to policy makers in selecting an appropriate vaccine for the population.

Background Malaria is the most deadly parasitic disease and continues to claim more than a half million of deaths across the world each year, mainly those of under-fives children in sub-Saharan Africa. The aim of this study was to determine the epidemiological, clinical and laboratory features of patients with severe malaria at the Centre Hospitalier Régional Amissa Bongo (CHRAB), a referral hospital in Franceville. Methods It was an observational descriptive study conducted at CHRAB over 10 months. All admitted patients at the emergency ward of all ages presenting with positive test to falciparum malaria diagnosed by microscopy and rapid test with clinical signs of severe illness describe by World Health Organization were enrolled. Results During this study, 1065 patients were tested positive for malaria, of them 220 had severe malaria. Three quarters (75.0%) were less than 5 years of age. The mean time to consultation was 3.5 ± 1 days. The most frequent signs of severity on admission were dominated by neurological disorders 92.27% (prostration 58.6% and convulsion 24.1%), followed by severe anemia 72.7%, hyperlactatemia 54.6%, jaundice 25% and respiratory distress 21.82%.The other forms such as hypoglycemia, haemoglobinuria, renal failure were found in low proportions Conclusion Severe malaria remains a public health problem affecting mostly children under 5 years. Classification of malaria helps identify the most severely ill patients and aids early and appropriate management of the severe malaria cases.

The geographic and evolutionary origins of the SARS-CoV-2 Omicron variant (BA.1), which was first detected mid-November 2021 in Southern Africa, remain unknown. We tested 13,097 COVID-19 patients sampled between mid-2021 to early 2022 from 22 African countries for BA.1 by real-time RT-PCR. By November-December 2021, BA.1 had replaced the Delta variant in all African sub-regions following a South-North gradient, with a peak Rt of 4.1. Polymerase chain reaction and near-full genome sequencing data revealed genetically diverse Omicron ancestors already existed across Africa by August 2021. Mutations, altering viral tropism, replication and immune escape, gradually accumulated in the spike gene. Omicron ancestors were therefore present in several African countries months before Omicron dominated transmission. These data also indicate that travel bans are ineffective in the face of undetected and widespread infection.

Cytokines are soluble mediators of the immune response, and their evolution influences the disease outcome. Gaining knowledge on cytokines has become important, as they can constitute biomarkers allowing the diagnosis of malaria and preventing severe forms of the disease. Here, we investigated 10 cytokines and their circulating levels in asymptomatic Gabonese children with Plasmodium falciparum infection living in urban, semi-urban and rural areas. Blood samples were collected from 273 schoolchildren (153 uninfected and 120 infected) aged 6 to 192 months. Hematological parameters were determined and P. falciparum diagnosis was performed using a rapid diagnosis test, microscopy and nested polymerase chain reaction (PCR). Plasma pro- [interferon (IFN)-γ, tumor necrosis factor (TNF)-α, interleukin (IL)-6, IL-12p70, IL-17A and IL-22] and anti-inflammatory [IL-10, IL-4, IL-13 and transforming growth factor (TGF)-β] cytokine levels were measured by enzyme-linked immunosorbent assay (ELISA) and compared between asymptomatic-infected and uninfected children. Results revealed that without distinction of area, IL-10 and IL-6 levels were higher in infected compared to uninfected children; however, the pro- and anti-inflammatory ratios (IL-6/IL-10 and TNF-α/IL-10) were similar. Furthermore, with area distinction significantly elevated levels of IL-10 in these asymptomatic children were always accompanied by either significantly low or high levels of a proinflammatory cytokine. Also, comparison between asymptomatic-infected children from the three areas showed significantly lower IL-17A, IL-22 and TGF-β levels in urban area compared to semi-urban and rural areas. These results suggest that asymptomatic malaria infections induce significantly high inflammatory cytokine levels without modifying the balanced between pro- and anti-inflammatory cytokines and underline the higher exposure to infections of children in rural areas.

Background The national malaria control policy in the Central African Republic (CAR) promotes basic, clinical, and operational research on malaria in collaboration with national and international research institutions. Preparatory work for the elaboration of National Strategic Plans for the implementation of the national malaria control policy includes developing the research component, thus requiring an overview of national malaria research. Here, this survey aims to provide an inventory of malaria research as a baseline for guiding researchers and health authorities in choosing the future avenues of research. Methods Data sources and search strategy were defined to query the online Medline/PubMed database using the “medical subject headings” tool. Eligibility and study inclusion criteria were applied to the selected articles, which were classified based on year, research institute affiliations, and research topic. Results A total of 118 articles were retrieved and 51 articles were ultimately chosen for the bibliometric analysis. The number of publications on malaria has increased over time from 1987 to 2020. These articles were published in 32 different journals, the most represented being the Malaria Journal (13.73%) and the American Journal of Tropical Medicine and Hygiene (11.76%). The leading research topics were drug evaluation (52.94%), expatriate patients (23.54%), malaria in children (17.65%), morbidity (13.7%), and malaria during pregnancy (11.76%). The publications’ authors were mainly affiliated with the Institut Pasteur of Bangui (41%), the French Military Medical Service (15.5%), and the University of Bangui (11.7%). Collaborations were mostly established with France, the UK, and the USA; some collaborations involved Switzerland, Austria, Pakistan, Japan, Sri Lanka, Benin, Cameroun, Ivory Coast, and Madagascar. The main sources of research funding were French agencies (28.6%) and international agencies (18.3%). Most studies included were not representative of the whole country. The CAR has the capacity to carry out research on malaria and to ensure the necessary collaborations. Conclusion Malaria research activities in the CAR seem to reflect the priorities of national policy. One remaining challenge is to develop a more representative approach to better characterize malaria cases across the country. Finally, future research and control measures need to integrate the effect of COVID-19.

Objectives Pregnancy-associated malaria (PAM) is a complex form of malaria. To prevent PAM, several African countries have adopted intermittent preventive treatment with sulfadoxine/pyrimethamine (IPT-SP). However, resistance to SP has been reported, associated with mutations in the genes Plasmodium falciparum dihydropteroate synthase (Pfdhps) and P. falciparum dihydrofolate reductase (Pfdhfr). The aim of this study was to investigate the prevalence of mutations in Pfdhfr and Pfdhps in P. falciparum isolates from rural areas of Gabon. Methods A cross-sectional survey of febrile patients (n = 202) who consulted Fougamou Health Center between February–May 2016 was performed. DNA was extracted from patient samples and the Pfdhfr and Pfdhps genes were genotyped using PCR-RFLP. Statistical analyses were performed. Results The malaria prevalence in febrile patients included in the study was 60.4% (122/202). The main parasite species was P. falciparum (96.7%; 118/122), followed by Plasmodium malariae (3.3%; 4/122). Genotypes on codons 16, 51, 59 and 108 of Pfdhfr were highly mutated (>96%). In Pfdhps, codons 436, 437, 540 and 613 also expressed high mutation rates. The prevalence of triple mutations of Pfdhfr VIRNI and AIRNI was 12.1% and 84.5%, respectively. The prevalence of mutant haplotypes of Pfdhps SGEA, SGKA and AGEA was 37.9%, 25.9% and 12.1%, respectively. The prevalence of quadruple mutants IRN-A and IRN-G was 20.0% and 93.1%, respectively, whereas quintuple mutants were found at 57.8% (IRN-GE) and 5.0% (IRN-AE). Conclusion Our data show a high prevalence of genotypes associated with SP resistance. Clinical trials to investigate the efficacy of IPT-SP are much needed.

The COVID-19 disease presents a large range of clinical manifestations and includes asymptomatic, mild, and severe cases. The level of severity is related to parameters associated with immunity, genetics, and biochemistry. Africa shows one of the lowest COVID-19 fatality rates but very few data on the biochemical markers of COVID-19 in patients and the factors associated with disease severity are available for the continent. In Gabon, the COVID-19 fatality rate is only 0.63% but almost no data on biomarkers in COVID-19 patients have been published. Both the number of COVID-19 cases and the mortality rate reported in Africa in general, and in Gabon in particular, are lower than in non-African countries. As such, understanding the factors associated with disease severity in Gabonese patients is a crucial step to better understand the disease in the African context and prepare for future COVID-19 waves and other epidemics of emerging diseases. Here, we compared biochemical and hematological markers among 753 Gabonese COVID-19 patients with asymptomatic (184/753), mild/moderate (420/753), and severe/critical (149/753) forms of the disease using an Analysis of Variance (ANOVA) or a Kruskal-Wallis (KW) test. We modeled these parameters together with comorbidities, age, and sex to predict factors associated with disease severity by using a "binomial generalized linear model" utilizing the "package" stats of R software version 4.0.2. Our results showed that almost all the biochemical and hematological parameters (except creatinine, phosphorus, D-dimers, platelets, and monocytes) varied according to disease severity. However, age and the dysfunction of organs like the kidney, liver, and lung together with the decrease of electrolytes (chloride, potassium, and sodium) are the best predictors of disease severity in Gabonese patients.

International audience; Since the onset of the COVID-19 pandemic, the SARS-CoV-2 viral dynamics in Africa have been less documented than on other continents. In Gabon, a Central African country, a total number of 37,511 cases of COVID-19 and 281 deaths have been reported as of December 8, 2021. After the first COVID-19 case was reported on March 12, 2020, in the capital Libreville, the country experienced two successive waves. The first one, occurred in March 2020 to August 2020, and the second one in January 2021 to May 2021. The third wave began in September 2021 and ended in November 2021. In order to reduce the data gap regarding the dynamics of SARS-CoV-2 in Central Africa, we performed a retrospective genotyping study using 1,006 samples collected from COVID-19 patients in Gabon from 2020 to 2021. Using SARS-CoV-2 variant screening by Real-Time Quantitative Reverse Transcription PCR (qRT-PCR) and whole genome sequencing (WGS), we genotyped 809 SARS-CoV-2 samples through qRT-PCR and identified to generated 291 new genomes. It allowed us to describe specific mutations and changes in the SARS-CoV-2 variants in Gabon. The qRT-PCR screening of 809 positive samples from March 2020 to September 2021 showed that 119 SARS-CoV-2 samples (14.7%) were classified as VOC Alpha (Pangolin lineage B.1.1.7), one (0.1%) was a VOC Beta (B.1.351), and 198 (24.5 %) were VOC Delta (B.1.617.2), while 491 samples (60.7%) remained negative for the variants sought. The B1.1 variant was predominant during the first wave while the VOC Alpha dominated the second wave. The B1.617.2 Delta variant is currently the dominant variant of the third wave. Similarly, the analysis of the 291 genome sequences indicated that the dominant variant during the first wave was lineage B.1.1, while the dominant variants of the second wave were lineages B.1.1.7 (50.6%) and B.1.1.318 (36.4%). The third wave started with the circulation of the Delta variant (B.1.617). Finally, we compared these results to the SARS-CoV-2 sequences reported in other African, European, American and Asian countries. Sequences of Gabonese SARS-CoV-2 strains presented the highest similarities with those of France, Belgium and neighboring countries of Central Africa, as well as West Africa.

Background Pediatric diarrhea caused by a range of pathogens, including intestinal parasites, is one of main causes of death among children under 5 years of age. The distribution of these parasitic infections overlaps in many environmental, socioeconomic and epidemiological settings. Their distribution and prevalence varies from region to region. In the current study, we assess the prevalence of intestinal parasites among pediatric patients with syndromic diarrheal disease living in Franceville, Gabon. Methods A cross-sectional study conducted in the Amissa Bongo Regional Hospital and Chinese-Gabonese Friendship Hospital in Franceville, between November 2016 and August 2017, enrolled a total of 100 diarrheic children between 0 and 180 months of age. Parasite detection in stool samples was performed using molecular diagnostic by PCR. Difference in means were tested by Student’s t test and ANOVA while principal component analysis was used to determine the correlation between parasite distributions and age groups. Results The overall prevalence of intestinal parasite infection was 61% (61/100). Hymenolepis sp and Cryptosporidium hominis/parvum were the most common parasites (31 and 19%, respectively), followed by Encephalitozoon intestinalis (15%), Trichuris trichiura (4%), Dientamoeba fragilis (4%), and Enterocytozoon bieneusi (2%). The polyparasitism rate was 19.7%, with 83.3% double and 16.7% triple infections. Protozoan infections (66.7%) were more prevalent than helminths infections (33.3%). Seasonal association of the circulation of intestinal parasite was statistically significant (p = 0.03). Correlations between different parasites was also observed. Conclusion The prevalence of intestinal parasitic infections is highest in diarrheic pediatric children. The prevalence of parasitic infections indicates that protozoa and helminths are the most common parasites in the Franceville environment. This study reinforces the importance of routine examination of diarrheic stool samples for the diagnostic of intestinal parasites. Further analyses are required to better understand the local epidemiology and risk factors associated with the transmission of intestinal parasites in Franceville, Gabon. Keyswords diarrhea, children, intestinal parasitic infections, molecular diagnostic, Franceville, Gabon.

COVID-19 is an emerging respiratory disease; it was declared a global pandemic by the World Health Organization. This survey aimed to describe the knowledge, attitudes, perception and practices of the Gabonese public towards COVID-19. This study was performed on 1016 participants. All participants filled in the questionnaire voluntarily, reporting demographic characteristics and answering questions assessing their level of knowledge, attitudes, perceptions and practice towards COVID-19. Among participants, there were 535 men and 476 women. The mean age of the participants was 33.2 ± 16.7 years old. Almost all participants (98.1%) said that they had heard about COVID-19 but only 2.8% knew the pathogenic agent responsible for COVID-19. More than 80% knew that the disease could be transmitted by greeting infected people (87.3%), kissing an infected person (90.0%), touching an infected doorknob (83.5%) and attending meetings (83.9%). The mean knowledge score was higher among younger than older participants, higher among participants living in urban areas than those living in rural areas and higher among participants with higher levels of education than those with lower levels of education. In general, respondents had good knowledge of COVID-19 and a positive attitude towards using protective measures; however, there were differences according to gender, age group, place of residence, professional group and level of education.

Early predictions forecasted large numbers of severe acute respiratory syndrome coronavirus (SARS-CoV-2) cases and associated deaths in Africa. To date, Africa has been relatively spared. Various hypotheses were postulated to explain the lower than anticipated impact on public health in Africa. However, the contribution of pre-existing immunity is yet to be investigated. In this study, the presence of antibodies against SARS-CoV-2 spike (S) and nucleocapsid (N) proteins in pre-pandemic samples from Africa, Europe, South and North America was examined by ELISA. The protective efficacy of N specific antibodies isolated from Central African donors was tested by in vitro neutralization and in a mouse model of SARS-CoV-2 infection. Antibodies against SARS-CoV-2 S and N proteins were rare in all populations except in Gabon and Senegal where N specific antibodies were prevalent. However, these antibodies failed to neutralize the virus either in vitro or in vivo. Overall, this study indicates that cross-reactive immunity against SARS-CoV-2 N protein was present in Africa prior to the pandemic. However, this pre-existing humoral immunity does not impact viral fitness in rodents suggesting that other human immune defense mechanisms could be involved. In Africa, seroprevalence studies using the N protein are over-estimating SARS-CoV-2 circulation.

Plasmodium falciparum is a parasite that causes asymptomatic or symptomatic malaria infections in humans depending on various factors. These infections are also a major cause of anemia in intertropical countries such as Gabon. Past studies have clearly demonstrated that inflammatory markers such as cytokines play a key role in the pathogenesis of malaria disease. However, the clinical manifestations of severe malaria vary according to the level of transmission and more information is needed to gain a better understanding of the factors involved. As such, the objective of this study was to investigate the circulating levels of nine cytokines in asymptomatic and symptomatic P. falciparum infections in Gabonese children and their roles in the pathogenesis of anemia. Blood samples were collected from 241 children aged 3 to 180 months in Lastourville, south-eastern Gabon. Diagnosis of P. falciparum infection was performed using Rapid Diagnosis Tests, microscopy and nested PCR. Levels in the plasma of the Th1 (IFN-γ, TNF-α, IL-6 and IL-12p70), Th17 (IL-17A and IL-22) and Th2 (IL-10, IL-4 and IL-13) cytokines were measured by ELISA. Data showed that IL-6, IFN-γ, IL-12p70, IL-10, and IL-13 levels were significantly higher in children with symptomatic P. falciparum infection compared to uninfected children. IL-10 levels were significantly higher in symptomatic children than in asymptomatic children, who had moderately increased levels compared to uninfected controls. Moreover, only IL-10 and IL-6 levels were significantly higher in children with severe malarial anemia compared to children with uncomplicated malaria who had significantly lower IL-10 levels than children with moderate malarial anemia. These data indicate that the progression of P. falciparum infection towards an advanced stage in children is accompanied by a significant increase in type Th1 and/or Th2 cytokines. These inflammatory mediators could serve as potential predictors of anemia for malaria patients.

Background: Evaluating malaria control strategies for pregnant women is essential. The objective of this study was to determine the factors influencing the frequency of prenatal consultations (PNC), the adherence to intermittent preventive treatment with sulfadoxine-pyrimethamine (IPT-SP) and its impact on the health of parturient women and their newborn babies living in semi-urban and rural areas of southeastern Gabon.Methods: This transversal study was performed at the Centre Hospitalier Régional Paul Moukambi de Koula-Moutou (CHRPMK). Information regarding age, frequency of prenatal consultations, obstetric history, use of malaria control measures, use of IPT-SP, malaria diagnostic of parturient women and their newborns, were collected with a questionnaire and from birth registers from January 1st 2018 to December 31st 2019.Results: In total, 2174 parturient women were included in the study. The mean age was 26.2 ± 6.99 years and 81.4% of parturient women attended at least four CPN. The proper attendance of PNC (at least 4 prenatal consultations) was linked with age (p< 0.001) and profession (aOR= 1.72 [1.27 - 2.37]; p< 0.001). The coverage rate of IPT-SP was 90% with a good adherence rate (at least three doses of IPT-SP) of 58.87%. The good adherence rate to IPT-SP was linked to profession (aOR= 1.65 [1.20 - 2.29]; p< 0.01) and age (p< 0.001). The mean weight of newborns was higher for babies whose mothers had received three doses of IPT-SP (p< 0,001) but the APGAR score was not influenced by the use of IPT-SP by the mother (p= 0.47). The prevalence of plasmodial infection was 3.10% (IC95%= [1.21 - 5]) and Plasmodium falciparum was responsible for 100% of infections. The prevalence of plasmodial infection was the same for all age groups (p> 0.06). No link was found between plasmodial infection, gravidity (p> 0.06) and domestic control measures (p≥ 0.05). A low birth weight was statistically linked to the mother’s plasmodial infection (OR= 9.42 [2.55 – 34.75]; p< 0.01). Furthermore, plasmodial infection was statistically linked to premature birth (OR= 69.25 [8.52 – 562.69]; p< 0.001).Conclusions: We observed a good attendance of women to prenatal counselling services in southeastern Gabon, though the adherence of IPT-SP is insufficient.

Background Malaria remains a major public health issue in the world despite a decline in the disease burden. However, though symptomatic malaria is diagnosed and treated, asymptomatic infections remain poorly known and support transmission. This study assessed the prevalence of symptomatic and asymptomatic plasmodial infections in three areas in Gabon to monitor and evaluate the impact of malaria. Methods A cross-sectional study was conducted at the Centre Interdisciplinaire de Recherches Médicales de Franceville (CIRMF). Febrile children and without fever, aged 6 months to 15 years from three localities (Franceville, Makokou, Lastoursville) in south-eastern Gabon were included in this study. The Plasmodium Spp infection was determined by microscopy and/or rapid diagnostic tests (RDT) followed by PCR according to the Snounou method. The data were recorded in Excel, and the statistical analyzes were performed using the software R version R 64x 3.5.0. Results Two thousand three hundred and eighty-one (2381) children were screened and included in this analysis. The mean age was significantly higher in asymptomatic children compared to symptomatic children. Hematological parameters varied significantly according to regions and clinical signs. The overall prevalence of Plasmodium infection was 40% (952/2381). In the urban area (Franceville) the prevalence of plasmodial infection was not significantly different between symptomatic and asymptomatic children. In contrast, a high prevalence of symptomatic plasmodial infection was found in infected children in rural and semi-rural areas. Among the three plasmodial species (Plasmodium falciparum, Plasmodium malariae, Plasmodium ovale) identified, Plasmodium falciparum was the most widespread, and its prevalence was not significantly different between symptomatic and asymptomatic children in the three localities. In rural and semi-rural areas, a higher or lower prevalence of Plasmodium malariae was demonstrated in asymptomatic children. Conclusion This study showed that the prevalence of plasmodial infection varied according to the regions and clinical signs. The main species was Plasmodium falciparum, but in asymptomatic children the prevalence of Plasmodium malariae was high in rural areas. To help fight malaria more effectively asymptomatic infections should be taken into account and treated.

Steede Seinnat Ontoua,1,&ast; Lady Charlene Kouna,1,&ast; Sandrine Lydie Oyegue-Liabagui,1,2 Dominique Fatima Voumbo-Matoumona,3 Diamella Nancy Moukodoum,1 Romeo Karl Imboumy-Limoukou,1 Jean Bernard Lekana-Douki1,4 1Unité d’Evolution, Epidémiologie et Résistance Parasitaire (UNEEREP), Centre Interdisciplinaire des Recherches Médicales de Franceville (CIRMF), Franceville, BP 769, Gabon; 2Ecole Doctorale Régionale d’Afrique Centrale en Infectiologie Tropicale (ECODRAC), Université de Sciences et Techniques de Masuku (USTM), Franceville, BP 876, Gabon; 3Départements des Masters/Licences, Parcours-Types des Sciences Biologiques, Faculté des Sciences et Techniques, Université Marien Ngouabi, Brazzaville, BP 69, Congo; 4Département de Parasitologie-Mycologie Médecine Tropicale, Faculté de Médecine, Université des Sciences de la Santé (USS), Libreville, BP 4009, Gabon&ast;These authors contributed equally to this workCorrespondence: Jean Bernard Lekana-DoukiUNEEREP-CIRMF, Franceville, B.P. 769, GabonTel +241 62521250; +241 6259590Email lekana_jb@yahoo.frPurpose: Plasmodium falciparum malaria remains a major public health challenge in sub-Saharan Africa. Plasmodium falciparum drug resistance mediated by polymorphisms in the Pfmdr1 gene contributes to the persistence of the disease on the African continent. This study investigated P. falciparum infection features and differences in the Pfmdr1 genotypes between symptomatic and asymptomatic malaria cases in a rural area in east-central Gabon.Patients and Methods: A total of 875 children aged from 5 to 185 months were screened for P falciparum infection using Optima-IT® rapid diagnostic tests and standard microscopy. Pfmdr1 polymorphisms at codons 86, 184 and 1246 were investigated using PCR-RFLP.Results: Among the 448 P. falciparum-infected children, 57.08% (n=250) were symptomatic and 42.92% (n=198) were asymptomatic (p < 0.0001). In a sub-set of 79 isolates, the Pfmdr1 wild-type N86 was more prevalent in symptomatic (100%) than in asymptomatic infections (70.7%) (p=0.007). The mutant 86Y and mixed 86N/Y genotypes were observed only in asymptomatic infections. The Y184 and 184F genotype prevalences (39.1% vs 19.4% and 60.9% vs 80.6%, respectively) were not significantly different between the two groups (p=0.097). The prevalence of the wild-type D1246 differed significantly between symptomatic (10.3%) and asymptomatic (100%) (p < 0.0001). The NFD and YFD haplotypes were more prevalent in asymptomatic than in symptomatic infections [(61.9% vs 31%; p=0.005) and (16.7% vs 0.0%; p=0.01)], whereas the NYD and YYD haplotypes were not significantly different between the two groups [(21.4% vs 14.3%, p=0.39) and (0.0% vs 7.1%, p=0.24)].Conclusion: Our results confirm a high transmission of P. falciparum infection in rural Gabon, with a high prevalence of asymptomatic carriage. The higher prevalences of wild-type N86 in symptomatic infections and of D1246 in asymptomatic infections suggest a pathogenicity associated with polymorphisms in Pfmdr1. These results highlight the need to monitor the efficacy of artemisinin-based combination therapies in Gabon.Keywords: symptomatic malaria, asymptomatic malaria, Pfmdr1, drug resistance, rural Gabon

BackgroundCOVID-19 is an emerging respiratory disease caused by severe acute respiratory syndrome coronavirus SARS-CoV-2. It has spread from China to more than 200 countries and has been declared a global pandemic by the World Health Organization (WHO). This survey aimed to describe the knowledge, attitudes, perception and practices (KAP) of the Gabonese public towards the COVID-19 disease.MethodsThis cross-sectional study was performed on 1016 participants aged 10 years and over in rural and urban area in south-east Gabon, using a questionnaire. All participants filled the questionnaire voluntarily, reporting demographic characteristics and answering questions assessing their level of knowledge, attitudes, perceptions and practice toward the COVID-19. ResultsAmong the 1016 participants, there were 535 men (52.7%) and 476 women (46.9%). The mean age of the participants was 33.2±16.7 years old. Almost all participants (98.1%) said that they had heard about COVID-19 but only 2.8% knew the pathogenic agent responsible for COVID-19. Only 20.9% of respondents thought that vaccination can protect them but 51.9% were looking forward to getting the vaccine when available. More than 80% knew that the disease could be transmitted by greeting infected people (87.3%), kissing an infected person (90.0%), touching an infected doorknobs (83.5%), and attending meetings (83.9%). The mean knowledge score was higher among younger than older participants, higher among participants living in urban area than those living in rural areas, and higher among participants with higher levels of education than those with lower levels of education.ConclusionIn general, respondents had good knowledge of COVID-19, and a positive attitude towards using protective measures. These results are encouraging in the fight against the spread of COVID-19 in Gabon. However, efforts are needed to improve the knowledge level in older participants, those living in rural areas and those with low levels of education. Awareness campaigns in local languages could, for example, be conducted to improve knowledge of the disease in rural areas.

Background: The seroprevalence of HIV in Gabon is 4.1%. This rate varies among its nine provinces and is estimated at 4.2% in the province of Nyanga. This variance is believed to be the result of a lack of information and beliefs regarding HIV transmission and prevention. There are currently scarce epidemiological data from this region of Gabon. We assessed the knowledge, attitudes and practices of women of childbearing age from Nyanga province towards HIV.Methods: A 13-day cross-sectional descriptive study of 631 women aged 15 to 49 years was conducted within the five departments of the province to assess their knowledge and attitudes about HIV, with particular emphasis on mother-to-child HIV transmission (MTCT). Household recruitment of participants was conducted and information was collected by means of a questionnaire. Correct answers were considered as indicating a basic knowledge of the topic assessed.Results: Around 90% of women (570/631) were of childbearing age but not pregnant during the survey, with a mean age of 28 years. Also, 10% (61/631) were pregnant. Among surveyed women, 99.2% had heard of HIV/AIDS and 81.8% knew at least one screening site for HIV. More than 83.6% knew that MTCT could occur during pregnancy, and 76.5% knew about transmission during breastfeeding. In addition, 86.5% knew that HIV couldn’t be transmitted through sharing food with an infected person. Similarly, 68.8% answered that HIV transmission cannot occur through mosquito bites. However, 45.8% of women said that HIV could be transmitted by witchcraft. For 81.6% of participants, HIV could be prevented by having a single monogamous sexual partner and protected sex. Seventy percent of the women were aware of antiretroviral therapy. More than 80% of the participants indicated that they had been screened overall, and 77.3% said that they had been offered HIV screening services during antenatal visits.Conclusions: Almost all women of childbearing age in Nyanga had heard of HIV, yet about half of them had poor knowledge of its modes of transmission. It is therefore imperative to carry out awareness campaigns in conjunction with HIV testing services to better understand the current prevalence of HIV infection in the region.

Rodents are reservoirs of numerous zoonotic diseases caused by bacteria, protozoans, or viruses. In Gabon, the circulation and maintenance of rodent-borne zoonotic infectious agents are poorly studied and are often limited to one type of pathogen. Among the three existing studies on this topic, two are focused on a zoonotic virus, and the third is focused on rodentPlasmodium. In this study, we searched for a wide range of bacteria, protozoa and viruses in different organs of rodents from the town of Franceville in Gabon. Samples from one hundred and ninety-eight (198) small mammals captured, including two invasive rodent species, five native rodent species and 19 shrews belonging to theSoricidaefamily, were screened. The investigated pathogens were bacteria from theRickettsiaceaeandAnaplasmataceaefamilies,Mycoplasmaspp.,Bartonellaspp.,Borreliaspp.,Orientiaspp.,Occidentiaspp.,Leptospiraspp.,Streptobacillus moniliformis,Coxiella burnetii, andYersinia pestis;parasites from classKinetoplastidaspp. (Leishmaniaspp.,Trypanosomaspp.),Piroplasmidaespp., andToxoplasma gondii; and viruses fromParamyxoviridae,Hantaviridae,FlaviviridaeandMammarenavirusspp. We identified the following pathogenic bacteria:Anaplasmaspp. (8.1%; 16/198),Bartonellaspp. (6.6%; 13/198),Coxiellaspp. (5.1%; 10/198) andLeptospiraspp. (3.5%; 7/198); and protozoans:Piroplasmasp. (1%; 2/198),Toxoplasma gondii(0.5%; 1/198), andTrypanosomasp. (7%; 14/198). None of the targeted viral genes were detected. These pathogens were found in Gabonese rodents, mainlyLophuromyssp.,Lemniscomys striatusandPraomyssp. We also identified new genotypes:CandidatusBartonella gabonensis and UnculturedAnaplasmaspp. This study shows that rodents in Gabon harbor some human pathogenic bacteria and protozoans. It is necessary to determine whether the identified microorganisms are capable of undergoing zoonotic transmission from rodents to humans and if they may be responsible for human cases of febrile disease of unknown etiology in Gabon.

Background: Gestational malaria remains one of the most complex forms of malaria. To fight it, several African countries adopted intermittent presumptive treatment with Sulfadoxine-Pyrimethamine (IPT-SP) and the use of preventive measures such as insecticide-treated bed nets (ITNs), indoor residual sprays (IRS) and popular education on good practices to fight against malaria. In Gabon a country of central Africa, no study has investigated the use of IPT-SP in rural areas since its implementation. The aim of this study was to investigate the adhesion level of pregnant women to IPT-SP, coverage of ITNs and IRS, and knowledge on the good practices about malaria in a rural area of Gabon. Using a questionnaire, we led a retrospective study including pregnant women from January 5th 2016 to January 31st 2018 and a cross-sectional survey including women seen for antenatal care and all febrile patients in consultation from February 2nd to May 31st 2018. Malaria was diagnosed using rapid diagnostic tests. Statistical analyses were done. Results: We included 607 pregnant women before their delivery. Women between 20 and 25 years old were the most prevalent (37.26%, n=229). Among them, 74.53% were unemployed and 47.21% living in the villages surrounding the rural town of Fougamou. The rate of adhesion to IPT-SP was 94.37% (n=573). Among them, 47.8% (n=274) had received 3 doses of IPT. Among the pregnant women included during the cross-sectional survey, only 8.7% (n=14) were infected with Plasmodium. Bed nets were used by 80.12% (n=129) of women. Conclusion: Data showed a near complete adhesion of IPT-SP in the rural area of Fougamou. Clinical trials are needed to investigate the efficacy of IPT-SP and antimalarial drug markers.

Human herpesvirus 8 (HHV-8) is the etiological agent of all forms of Kaposi&rsquo, s sarcoma (KS). K1 gene studies have identified five major molecular genotypes with geographical clustering. This study described the epidemiology of HHV-8 and its molecular diversity in Gabon among Bantu and Pygmy adult rural populations and KS patients. Plasma antibodies against latency-associated nuclear antigens (LANA) were searched by indirect immunofluorescence. Buffy coat DNA samples were subjected to polymerase chain reaction (PCR) to obtain a K1 gene fragment. We studied 1020 persons, 91% were Bantus and 9% Pygmies. HHV-8 seroprevalence was 48.3% and 36.5% at the 1:40 and 1:160 dilution thresholds, respectively, although the seroprevalence of HHV-8 is probably higher in Gabon. These seroprevalences did not differ by sex, age, ethnicity or province. The detection rate of HHV-8 K1 sequence was 2.6% by PCR. Most of the 31 HHV-8 strains belonged to the B genotype (24), while the remaining clustered within the A5 subgroup (6) and one belonged to the F genotype. Additionally, we reviewed the K1 molecular diversity of published HHV-8 strains in Africa. This study demonstrated a high seroprevalence of HHV-8 in rural adult populations in Gabon and the presence of genetically diverse strains with B, A and also F genotypes.

Background Better knowledge of endogenous germs and their associated demographic and environmental risk factors in a locality are essential to treat childhood diarrheal diseases. The aim of the study was to identify and characterize bacterial and parasitic pathogens responsible for childhood diarrhea, and to identify environmental risk factors associated with diarrhea in children under 5 years old living in Koula-Moutou, East-Central Gabon. Methods A cross-sectional study was performed from May 2016 to February 2018. One-hundred and thirty-two (132) children under 5 years old were enrolled. The detection of pathogens in stool samples was performed using microscopic examination and MIF concentration for parasites, and conventional culture on selective media for enterobacteria. Results The prevalence of diarrheal pathogens was 46.1%, including bacterial enteropathogens (25.5%) and parasites (20.6%). A total of 228 pathogenic organisms were isolated, including 199 bacterial strains (87.3%) and 29 parasites (12.7%). The specific richness of the isolated enterobacteria was 24 species with a high prevalence of E. coli (39.8%), including 26.7% for the diarrheal cases and 13.1% for the controls. Twelve (12) parasite species were also isolated and the most common types of parasites were rhizopods (44.8%), which accounted for 37.9% of the diarrheal cases and 6.9% of the controls. Univariate analysis showed that the presence of watercourses (OR = 3.37) and domestic animals (OR = 1.65) were significant risk factors for diarrhea. Conclusion The findings show a high prevalence of bacterial enteropathogens but a low rate of parasites and bacteria-parasite co-infection in the study area. Risk factors associated with diarrhea among children under 5 years old were the presence of watercourses and domestic animals. These findings highlight the need to strengthen the routine examination of diarrheic stool samples for the diagnosis of pathogenic organisms. Further analyses are required to better understand the etiologies and risk factors associated with the transmission of bacteria and parasites in rural, semi-urban and urban regions of Gabon.

Background There is little information on the social perception of malaria and the use of preventative measures in Gabon, especially in rural areas. Adequate knowledge of malaria prevention and control can help in reducing the burden of malaria among vulnerable groups, particularly pregnant women and children under 5 years old living in malaria-endemic settings. This study was designed to assess the prevalence of malaria and the knowledge and attitude towards this disease in households in Nyanga Province. Methods A cross-sectional study was conducted to assess malaria knowledge, prevention practices and prevalence of the malaria infection in five departments of Nyanga Province. Plasmodial infection was diagnosed in children ≤ 5 years of age and women aged 15-49 years using rapid diagnostic tests. A questionnaire was administered randomly to women aged 15–49 years and to the parents or guardians of children aged ≤ 5 years in 535 households during a 2-week period in March 2018. Overall, the respondents’ socio-demographic characteristics, knowledge of malaria, malaria prevention practices and malaria prevalence were evaluated and compared across the five departments. Results Data from a total of 1,307 participants were included in this study, including 631 women of childbearing age (61 of them pregnant) and 676 children. Practically the entire (97.7%) interviewed population had heard about malaria and attributed the cause of malaria to a mosquito bite (95.7%). This survey revealed that the reported rate of reported bed-net use was 73.3%. The study observed an average malaria parasite prevalence of 13.9%. All departmental capitals of Nyanga Province had a significant level of malaria infection except for Mayumba where no plasmodial infection was found. Conclusion High malaria prevalence is found in the departmental capital cities of Nyanga Province. This study reveals that respondents have a high knowledge of the malaria symptoms, its mode of transmission and preventive measures. Despite this high level of knowledge of the disease and its preventive measures, the incidence of malaria remains relatively high in this rural community highlighting the need for other types of interventions.

Background: There is little information on the social perception of malaria and the use of preventative measures in Gabon, especially in rural areas. Adequate knowledge of malaria prevention and control can help in reducing the burden of malaria among vulnerable groups, particularly pregnant women and children aged under 5 years old living in malaria endemic settings. This study was designed to assess the prevalence of malaria and the knowledge and attitude towards this disease in households in the Nyanga Province. Methods: A cross-sectional study was conducted to assess malaria knowledge, prevention practices and prevalence of the infection in five departments of the Nyanga Province. Malaria infection was confirmed using rapid diagnostic tests. A questionnaire was administered randomly to 535 households during a two weeks period in March 2018. Overall, the respondents’ socio-demographic characteristics, knowledge on malaria, malaria prevention practices and malaria prevalence were evaluated and compared across the five departments. Results: Data was collected on 1,307 participants were included in this study, 631 women of childbearing age (including 61 pregnant women) and 676 children. Practically the entire (97.7%) interviewed population had already heard about malaria and attributed the cause of malaria to a mosquito bite (95.7%). This survey revealed that the bed net coverage rate was 73.3%. The study observed an average malaria parasite prevalence of 13.9%. All departments of Nyanga province had significant level of malaria infection except for the Mayumba department where no plasmodial infection was found. The overall prevalence of the plasmodial infection was significantly higher in children and pregnant women compared to adults in the cities of Tchibanga and Moabi. Conclusion: Malaria is highly prevalent in the province of Nyanga. Our findings show that children under five and pregnant women are more vulnerable to malaria in this area of the country. This study reveals that respondents have a high knowledge of mode of transmission, malaria symptoms and preventive measures. Despite this high level of knowledge of the disease and its preventive measures, the incidence of malaria remains relatively high in this rural community highlighting the need for continuous strategic interventions particularly health awareness and educational programs

Summary The search for novel chemical classes of anti-malarial compounds to cope with the current state of chemoresistance of malaria parasites has led to the identification of Plasmodium falciparum aminopeptidase 1 (PfA-M1) as a new therapeutic target. PfA-M1, known to be involved in the hemoglobin digestion cascade which helps to provide most of the amino acids necessary to the parasite's metabolism, is currently considered as a promising target for anti-malarial chemotherapy. However, its immunogenic properties have not yet been tested in the Gabonese population. In Gabon, the prevalence of malaria remains three times higher in semi-urban areas (60·12%) than in urban areas (17·06%). We show that malaria-specific PfA-M1 antibodies are present in children and increase with the level of infection. Children living in semi-urban areas have higher anti-PfA-M1 antibody titers (0·14 ± 0·02 AU) than those living in urban areas (0·08 ± 0·02 AU, P = 0·03), and their antibody titers increase with age (P

Background: There is little information on the social perception of malaria and the use of preventative measures in Gabon, especially in rural areas. Adequate knowledge of malaria prevention and control can help in reducing the burden of malaria among vulnerable groups, particularly pregnant women and children aged under 5 years old living in malaria endemic settings. This study was designed to assess the prevalence of malaria and the knowledge and attitude towards this disease in households in the Nyanga Province. Methods: A cross-sectional study was conducted to assess malaria knowledge, prevention practices and prevalence of the infection in five departments of the Nyanga Province. Malaria infection was confirmed using rapid diagnostic tests. A questionnaire was administered randomly to 535 households during a two weeks period in March 2018. Overall, the respondents’ socio-demographic characteristics, knowledge on malaria, malaria prevention practices and malaria prevalence were evaluated and compared across the five departments. Results: Data was collected on 1,307 participants were included in this study, 631 women of childbearing age (including 61 pregnant women) and 676 children. Practically the entire (97.7%) interviewed population had already heard about malaria and attributed the cause of malaria to a mosquito bite (95.7%). This survey revealed that the bed net coverage rate was 73.3%. The study observed an average malaria parasite prevalence of 13.9%. All departments of Nyanga province had significant level of malaria infection except for the Mayumba department where no plasmodial infection was found. The overall prevalence of the plasmodial infection was significantly higher in children and pregnant women compared to adults in the cities of Tchibanga and Moabi. Conclusion: Malaria is highly prevalent in the province of Nyanga. Our findings show that children under five and pregnant women are more vulnerable to malaria in this area of the country. This study reveals that respondents have a high knowledge of mode of transmission, malaria symptoms and preventive measures. Despite this high level of knowledge of the disease and its preventive measures, the incidence of malaria remains relatively high in this rural community highlighting the need for continuous strategic interventions particularly health awareness and educational programs

The epidemiology of febrile illness etiologies is under-explored in resource-poor settings. Establishing a local repertory of microorganisms circulating in blood of febrile and afebrile people is important for physicians. Blood was collected from 428 febrile and 88 afebrile children in Makokou (Gabon) and analyzed using polymerase chain reaction. Plasmodium spp. were the pathogens, which were most detected in febrile children (69.6%; 298/428) and in afebrile children (31.8%; 28/88) (P < 0.0001). Plasmodium falciparum was the most prevalent species in both febrile and afebrile children (66.8% and 27.3%, respectively). No differences were observed between febrile and afebrile children for Plasmodium malariae and Plasmodium ovale (8.2% versus 10.2% and 3.3% versus 3.4%, respectively). Triple infection with P. falciparum, P. malariae, and P. ovale was also detected in 1% of febrile children (4/428). Filariasis due to Mansonella perstans was detected in 10 febrile patients (2.3%), whereas Loa loa was detected in both febrile and afebrile children (1.4% and 2.3%, respectively). Bacterial DNA was detected in only 4.4% (19/428) of febrile children, including 13 (68.4%) who were coinfected with at least one Plasmodium species. These were Haemophilus influenzae (1.6%, 7/428), Streptococcus pneumoniae and Staphylococcus aureus (1.2%, 5/428), and Rickettsia felis (0.9%, 4/428). Coxiella burnetii, Bartonella spp., Borrelia spp., Tropheryma whipplei, Anaplasma spp., Leptospira spp., Streptococcus pyogenes, and Salmonella spp. were not detected. This study also highlights the over-prescription and the overuse of antibiotics and antimalarials. Overall, malaria remains a major health problem in Makokou. Malaria control measures must be reconsidered in this region.

Background Pediculus humanus, which includes two ecotypes (body and head lice), is an obligate bloodsucking parasite that co-evolved with their human hosts over thousands of years, thus providing a valuable source of information to reconstruct the human migration. Pediculosis due to head lice occurred each year throughout the world and several pathogenic bacteria, which are usually associated with body lice, are increasingly detected in them. In Gabon, where this pediculosis is still widespread, there is a lack of data on genetic diversity of head lice and their associated bacteria. Methods This study aimed to investigate the phylogeny of head lice collected in Gabon and their associated bacteria, using molecular tools. Between 26 March and 11 April 2018, 691 head lice were collected from 86 women in Franceville. We studied the genetic diversity of these lice based on the cytochrome b gene, then we screened them for DNA of Bartonella quintana, Borrelia spp., Acinetobacter spp., Yersinia pestis, Rickettsia spp., R. prowazekii, Anaplasma spp. and C. burnetii, using real time or standard PCR and sequencing. Results Overall 74.6% of studied lice belonged to Clade A, 25.3% to Clade C and 0.1% to Clade E. The phylogenetic analysis of 344 head lice yielded 45 variable positions defining 13 different haplotypes from which 8 were novel. Bacterial screening revealed the presence of Borrelia spp. DNA in 3 (0.4%) of 691 head lice belonging to Clade A and infesting one individual. This Borrelia is close to B. theileri (GenBank: MN621894). Acinetobacter spp. DNA has been detected in 39 (25%) of the 156 screened lice; of these 13 (8.3%) corresponded to A. baumannii. Acinetobacter nosocomialis (n = 2) and A. pittii (n = 1) were also recorded. Conclusions To of our knowledge, this study is the first to investigate the genetic diversity of head lice from Gabon. It appears that Clade C is the second most important clade in Gabon, after Clade A which is known to have a global distribution. The detection of Borrelia spp. DNA in these lice highlight the potential circulation of these bacteria in Gabon.